The present invention relates to a turn signal switching device to actuate the turn signal lamps of an automobile, and more specifically, to a turn signal switching device for an automobile comprising a turn signal switch which actuates a directional turn signal lamp when moved in a desired direction and a self-cancel mechanism which restores the turn signal switch automatically to a neutral position in response to a return-rotating operation of a steering wheel. The switch and the self-cancel mechanism are constructed in a respectively separated form and connected by mechanically engaging them with each other when they are fitted to a steering column.
In the conventional turn signal for automobile, as shown by an embodiment of the prior art shown in FIGS. 1 and 2, for example, a self-cancel mechanism consisting of a cancel cam 1, a spring-fitted member 2, a moving member 3 and a cancel rotor 4 rotated together with a steering wheel 7 and a turn signal switch 28 actuated by the operation of a control lever 5 attached to the aforesaid moving member 3 have been mounted on a predetermined position at the upper face portion and the lower face portion of a supporting member 6 and installed integrally on the central lower face portion of the steering wheel 7. However, such traditional turn signal for automobile has incurred some shortcomings, i.e., the form and the operating method of the control lever 5 are limited by its relation with the self-cancel mechanism and, for example, it becomes an incoherent specific element even in combination with other various control switches. Moreover, the construction of the turn signal switch 28 is also restricted, making it difficult to simplify the mechanism. In order to overcome such disadvantages, e.g., as shown in FIG. 3, a turn signal for an automobile is known wherein a cancel detector 40 and a turn signal switch 38 having an automatic return mechanism have been composed separately and so arranged to return automatically a control lever 8 of the turn signal switch 38 by connecting to a flasher unit 39 with a so-called electrical means. This turn signal for an automobile has also had such drawback that the number of component parts including a semiconductor element 9, capacitor 10, resistor 11 and solenoid 12 increases and results in a cost increase.
In FIG. 3, an ignition switch 31 is fitted between a d-c power supply 32 and the turn signal switch 38. A diode 33 to absorb surge is fitted between the transistor 9 and the ignition switch 31. Resistors 34 and 35 are respectively connected in series to the base of the transistor 9. A left-side turn signal lamp 36 and a right-side turn signal lamp 37 are connected to the output side of the flasher unit 39.
The present invention has been made to atone for the abovediscussed shortcomings. Namely, the feature thereof is to provide a turn signal for an automobile wherein a sefl-cancel mechanism and a turn signal switch are separated and composed independently of each other. When attaching them to the steering column of automobile, for example, by connecting the control lever of the self-cancel mechanism and the turn signal switch mechanically with a simple engaging means by a boss and a hollow, they can be operated in conjunction with each other. The turn signal switch can be mounted in a relatively free, isolated and desired position. For example, the switch can be fitted combined with other various control switches and a greater latitude is allowed in the form and operating method of the control lever as a result of the restrictions having largely been relaxed, thus enabling to make the combination simpler and at a lower cost.